A wide range of electronic devices, including mobile wireless communication devices, personal digital assistants (PDAs), laptop computers, desktop computers, digital cameras, digital recording devices, and the like, include one or more embedded light sensors to enable applications to perform one or more light sensing operations. For example, an indoor/outdoor detection application may utilize light sensor data to detect whether the electronic device is indoors or outdoors. Similarly, the electronic device may include an electronic display (e.g., screen) where an automatic screen-brightness application adjusts the brightness of the screen based on the light sensor data. Further light-based applications may include sun intensity detection for a health-related application, or a white balancing application for adjusting the color of images captured by the electronic device.
Light sensors are typically low power (e.g., around 0.1 mA per hour) and may be implemented in a variety of ways depending on the make or model of the electronic device. In some devices, the light sensor is implemented as an ambient light sensor (ALS), which may be comprised of one, or in some cases, a few photodetectors. In other implementations the light sensor may be a Red Green Blue (RGB) sensor that detects intensities of red, green, and blue light. Similarly, a light sensor may be implemented as an ultraviolet detector that detects the intensity of ultraviolet light. The variations in the types, sensitivity, and even the circuitry that are included in the available light sensors included in various devices creates device-to-device variations in the resultant light sensor data.
Even still, various devices may physically locate the light sensor on the electronic device in a variety of positions. For example, a certain mobile device may embed a light sensor on a backside of the mobile device near a camera of the mobile device, while another mobile device may embed the light sensor on a front side of the mobile device, near the front-facing display.
These device dependent light sensors currently imply device dependent light-based applications. That is, each light-based application typically requires some knowledge of the device that it is running on as well as a known calibration factor for calibrating light sensor data that is acquired from the specific light sensor that is included on that device. In some applications this means storing, or otherwise obtaining a sizeable list of calibration factors for each possible device that may be running the light-based application. However, the large number of different devices in the market jeopardizes applications based on device dependent light-sensors data.